Fabrication of DRAM and other semiconductor devices with an insulating film using a wet rapid thermal oxidation process

ABSTRACT

A method of fabricating a semiconductor device includes depositing a dielectric film and subjecting the dielectric film to a wet oxidation in a rapid thermal process chamber. The technique can be used, for example, in the formation of various elements in an integrated circuit, including gate dielectric films as well as capacitive elements. The tight temperature control provided by the RTP process allows the wet oxidation to be performed quickly so that the oxidizing species does not diffuse significantly through the dielectric film and diffuse into an underlying layer. In the case of capacitive elements, the technique also can help reduce the leakage current of the dielectric film without significantly reducing its capacitance.

BACKGROUND

[0001] The present invention relates generally to semiconductor devicesand, more particularly, to the formation of a dielectric film using awet rapid thermal oxidation process.

[0002] Insulating materials, such as dielectrics, used in semiconductordevices are selected based on their electrical or other properties andtheir intended use. For example, a typical DRAM device can include afirst area assigned to a memory cell array and a second area assigned toperipheral circuits. The memory cells in the cell array include atransistor coupled in series with a stacked-type or other storagecapacitor. The transistor includes a gate dielectric layer such as anoxide. The storage capacitor, which stores charge to represent data,also includes a dielectric material disposed between two electrodes.

[0003] It often is desirable to select a dielectric material having ahigh dielectric constant for enhanced capacitance. For example, atantalum oxide (Ta₂O_(x)) film formed by chemical vapor deposition (CVD)has a high dielectric constant (ε_(r)) of about 25 to 30. Such a filmcan provide good step coverage and can be fabricated relatively easilycompared to other insulating films having high dielectric constants. Thetantalum oxide film typically is deposited as an oxygen-deficient oxide,and such oxygen deficient films typically are leaky. To improve theleakage current properties of the tantalum oxide film, an oxidizingtreatment can be performed following deposition of the film.

[0004] Some oxidation processes are performed at elevated temperaturesfor an extended duration which can result, for example, in the diffusionof oxidizing species through the dielectric layer so that more oxygen isincorporated into the insulating film. This results in a betterinsulating film. Other defects, however, such as pinholes, can result inleakage current and, therefore, in an insulating film having a breakdownvoltage that is not as high as desirable. Dielectric films with suchdefects do not have sufficiently high capacitance for the memory cellsrequired for DRAMs of 256 megabits and larger. Thus, it is desirable toimprove the techniques for enhancing the properties of tantalum oxideand other dielectric films used in DRAM and other semiconductor devices.

SUMMARY

[0005] In general, a method of fabricating a semiconductor deviceincludes depositing a dielectric film and subjecting the dielectric filmto a wet oxidation in a rapid thermal process chamber. The technique canbe used, for example, in the formation of various elements in anintegrated circuit, including gate dielectric films as well ascapacitive elements.

[0006] In one particular aspect, a method of fabricating a semiconductordevice includes depositing a dielectric film over an active region of asemiconductor substrate to form a gate of a transistor and subjectingthe dielectric film to a wet oxidation in a rapid thermal processchamber. For example, steam can be provided to a vicinity of thedielectric film while the substrate with the dielectric film is in therapid thermal process chamber.

[0007] Similarly, according to another aspect, a method of fabricating acapacitive element includes forming a lower electrode of the capacitiveelement. A dielectric film is deposited over the lower electrode and issubjected to a wet oxidation in a rapid thermal process chamber, forexample, by providing steam to a vicinity of the dielectric film. Anupper electrode then is formed over the dielectric film.

[0008] Various implementations include one or more of the followingfeatures. The dielectric film initially deposited can be anoxygen-deficient film and can include a material having a dielectricconstant of at least about 25. Exemplary dielectric materials that canbe deposited include tantalum oxide, silicon nitride, barium strontiumtitanate, strontium titanate, lead zirconium titanate and strontiumbismuth tantalate, among others. In some implementations, the dielectricfilm is deposited by chemical vapor deposition.

[0009] One of several techniques can be used to provide steam to avicinity of the insulating film. Such techniques include using a bubbledwater vapor system, a pyrogenic system or a catalytic system, orgenerating steam in the chamber in situ.

[0010] The temperature, duration and amount of steam can be selected tooptimize the oxidation process to obtain a film that is less prone toleakage. For example, in some implementations, the temperature in therapid thermal process chamber can be about 450° C. or higher. Ingeneral, the wet rapid thermal oxidation can be performed for a durationsuch that the oxidizing species does not diffuse significantly throughthe film. In particular, the duration can be selected so that theoxidizing species does not significantly affect the capacitive and otherproperties of the insulating film and so that it does not oxidize filmsunder the insulating dielectric. Exemplary durations are on the order ofonly several minutes, and typically can be as short as less than oneminute.

[0011] In some implementations, it is also desirable to subject theinsulating film to a heat treatment in an ambient comprising astabilizing gas such as nitrogen, oxygen, nitrogen oxide, or nitrousoxide. The heat treatment can help crystallize or otherwise stabilizethe electrical and other properties of the film. The heat treatment canbe performed either prior to or after subjecting the insulating film tothe wet oxidation. In some cases, the heat treatment also is performedin a rapid thermal process chamber.

[0012] One or more of the following advantages are present in someimplementations. Performing a wet oxidation process in an RTP chamber tocondition the dielectric film can help reduce the leakage current of thefilm without significantly reducing its capacitance. In particular, thetight temperature control provided by the RTP process allows the wetoxidation to be performed quickly so that the oxidizing species does notdiffuse significantly through the dielectric film and reduce oradversely affect the capacitance of the structure.

[0013] With respect to the formation of gate dielectric films, usingmaterials which have relatively high dielectric constants allows thegate dielectric to be made relatively thick and yet still provide acapacitance whose value is similar to thinner gates. The thickerdielectric layer can help reduce the adverse affects of gate hardeningcaused, for example, by boron penetration. Furthermore, the oxygencontent of the as-deposited film can be increased by subjecting the filmto the wet RTP oxidation. The electrical properties of the gatedielectric film can, thus, be enhanced.

[0014] Other features and advantages will be readily apparent from thefollowing detailed description, the accompanying drawings, and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a cross-section of an exemplary semiconductor deviceaccording to the invention.

[0016]FIGS. 2 and 3 are cross-sectional diagrams illustrating detailsfor fabricating a gate insulating layer according to the invention.

[0017]FIG. 4 illustrates an exemplary rapid thermal process (RTP)chamber for use in the present invention.

[0018]FIGS. 5 through 7 are cross-sectional diagrams illustratingdetails for fabricating capacitive elements of the memory deviceaccording to the invention.

[0019]FIG. 8 is a flow chart showing various steps of conditioning aninsulating film according to the invention.

DETAILED DESCRIPTION

[0020] Referring to FIG. 1, an exemplary semiconductor memory device 1includes an n-type well 4 formed in a p-type silicon substrate 2, and ap-type well 6 formed in the n-type well 4. At the surface of the p-typewell 6, a pair of transistors 8 are formed and constitute a memory cellof the memory device 1. Each of the transistors 8 includes n-typesource/drain regions 10A, 10B, a gate dielectric film 12, and a gateelectrode 14. The gate electrode 14 can include a polycrystallinesilicon film 16 and a silicide film 18 stacked above the gate dielectricfilm 12. Field oxide regions 15 separate the transistors 8 from otherdevices formed on the semiconductor wafer.

[0021] Each transistor 8 is covered with a first interlayer insulatingfilm 20. A contact hole 22 is formed through the insulating film 20 andreaches the source/drain region 10B common to the pair of transistors 8.A bit line 24 is connected to the source/drain region 10B through thecontact hole 22.

[0022] The bit line 24 is covered with a second interlayer insulatingfilm 26. Capacitive elements are formed above the insulating film 26.The stacked-type capacitive elements include a lower electrode 30, acapacitor insulating film 32, and an upper electrode 36. Each of thepaired lower electrodes 30 is electrically connected to a respective oneof the source/drain regions 10A through contact holes 38 which extendthrough the first and second interlayer insulating films 20, 26.

[0023] The capacitive elements are covered with a third interlayerinsulating film 40, and electrodes 42 are provided on the surface of thethird interlayer insulating film.

[0024] Further details for fabricating the gate insulating layer 12 aredescribed with reference to FIGS. 2 and 3. Referring to FIG. 2, adielectric film 12A is formed over the surface of the semiconductorwafer, for example, by a CVD process. Preferably, the dielectric filmhas a relatively high dielectric constant Er. For example, a lowpressure CVD apparatus with a source gas comprisingpentaethoxyltanatalum (Ta(OC₂H₅)₅) gas and oxygen can be used to form atantalum oxide (Ta₂O_(x)) film 12A having a dielectric constant ε_(r) ofabout 25 to 30. The deposited film 12A can be either an amorphous orcrystalline film. In other implementations, a silicon nitride(Si_(x)N_(y)) film can be deposited as the film 12A.

[0025] After the dielectric film 12A is deposited or grown, the film issubjected to a densifying treatment by which a film 12 (FIG. 3) isformed. The densifying treatment includes heating the semiconductorwafer to stabilize and/or crystallize the film 12A and includessubjecting the wafer to a wet oxidation in a rapid thermal process (RTP)chamber. The wet RTP oxidation process helps raise the oxygen content ofthe resulting film 12. If Si_(x)N_(y) is used as the film 12A, then thewet RTP oxidation treatment will result in a silicon oxynitride film 12.

[0026] Using materials such as tantalum oxide or silicon nitride whichhave relatively high dielectric constants allows the gate insulatinglayer to be made thicker than the typical 30-40 Å and yet still providea capacitance whose value is similar to the thinner gate layers. Thethicker insulating layer also can help reduce the adverse affects ofgate hardening caused by boron penetration. Furthermore, the oxygencontent of the as-deposited film 12A can be increased by subjecting thefilm 12A to the wet RTP oxidation. The electrical properties of the filmcan, thus, be enhanced.

[0027] Referring to FIG. 4, an exemplary RTP chamber 50 for use in theforegoing technique includes a substrate support structure 52. Asemiconductor wafer 54 with the insulating film 12A formed thereon ismounted on the support structure 52 and is heated by a heating element56 located above the wafer. A reflector 58 mounted beneath the wafer 54forms a reflecting cavity for enhancing the emissivity of the wafer.During processing, an inert gas 60 such as argon (Ar) can be provided tothe chamber interior to help purge the chamber 50. Steam 62 for the wetoxidation can be provided from a source external to the chamber 50 orcan be generated in situ within the chamber. Using an RTP process forthe wet oxidation provides precise temperature control and allowsoxidation of the film 12A to be performed quickly. In someimplementations, the RTP chamber 50 in which the wet oxidation iscarried out is part of a cluster system.

[0028] The steam for the wet oxidation can be provided to the interiorof the RTP chamber in the vicinity of the film 12 in various ways. Forexample, a bubbled water vapor technique can be used in which a waterreservoir external to the interior of the RTP chamber is heated togenerate steam. The steam then is carried to the interior of the chamber50 by a carrier gas such as Ar.

[0029] Alternatively, a pyrogenic system can be used in which hydrogen(H₂) and oxygen (O₂) gases are mixed together and heated by a torch toform steam or water vapor. The vapor then is carried to the chamberinterior via a duct.

[0030] In yet other embodiments, a catalytic system can be used togenerate steam or water vapor from a mixture of H₂ and O₂ gases.Platinum or another noble metal can be used as the catalyst.

[0031] According to another embodiment, an in situ steam generationprocess is used in which H₂ and O₂ gases are mixed within the chamber50. Heat from the wafer 50 can serve as the catalyst for forming steamin the vicinity of the wafer.

[0032] If a mixture of H₂ and O₂ gases is used to form the steam,suitable ratios of H₂ gas to O₂ gas are in the range of about 0.1 toabout 0.80. In general, the higher the ratio of H₂ gas to O₂ gas, themore aggressive is the oxidation process. The ratio of steam relative toother gases in the chamber 50 should be at least as high as 0.005, andpreferably is in the range of about 0.1 to about 0.5, although lesser orgreater amounts also can be used.

[0033] In various implementations, temperatures in the range ofapproximately 450° C. to about 1050° C. are suitable for the RTPprocess. More specifically, temperatures greater than about 600° C. aredesirable, as are temperatures in the range of about 750° C. to about950° C., particularly for crystalline films. For non-crystalline films,however, a lower temperature in the range of about 450° C. to about 750°C. can be used. The optimal pressure in the chamber will vary dependingon the particular RTP system and wet oxidation technique used. Ingeneral, the pressure can be at about atmospheric pressure, although ifthe H₂ and O₂ gases are combined in the chamber 50, then the pressureshould be kept lower, for example, around 1 millitorr. The wet oxidationcan be performed for as short a duration as a spike anneal or as long asseveral minutes. Preferably, however, the wet oxidation lasts for aduration in the range of about twenty to sixty seconds.

[0034] In some cases it also may be desirable to subject the gatedielectric film 12 to a heat treatment in an ambient comprising astabilizing gas. Such as heat treatment in the presence of a stabilizinggas can be performed either prior to or subsequent to the wet RTPoxidation process. Further details of the heat treatment using astabilizing gas are discussed below with reference to FIG. 8.

[0035] Following formation of the gate dielectric film 12, the gateelectrodes 14, the first interlayer insulating film 20, the contact hole22, the bit line 24, the second interlayer insulating film 26, and thecontact hole 38 can be formed using known techniques.

[0036] Once the second interlayer insulating film 26 and the contacthole 38 are formed, a polycrystalline silicon film is deposited, forexample, using a CVD process. The polycrystalline film can be doped withphosphorous and patterned to form the lower electrode 30. A rapidthermal nitriding treatment then can be performed to form a siliconSi_(x)N_(y) over the polycrystalline film.

[0037] In general, the techniques described above with respect to thegate dielectric film 12 also can be used to form the insulating film 32for the capacitive elements. Preferably, the film 32 includes a materialwith a relatively high dielectric constant ε_(r). Suitable materialsinclude, among others, Ta₂O_(x), Si_(x)N_(y), barium strontium titanate(Sr_(x)Ba_(1-x)TiO₃), strontium titanate (SrTiO₃), lead zirconiumtitanate (PbZrTiO₃) and strontium bismuth tantalate(Sr_(x)Bi_(y)Ta_(z)O₉). For example, as previously noted, Ta₂O_(x) has adielectric constant of about 25 to 30. Sr_(x)Ba_(1-x)TiO₃ can have adielectric constant as high as about 300, although the polar nature ofSr_(x)Ba_(1-x)TiO₃ may make it somewhat less desirable for someapplications.

[0038] In one exemplary implementation, a tantalum oxide film 32A (FIG.5) is formed over the surface of the interlayer insulating film 26including the surface of the lower electrode 30 by a CVD process. Asdescribed above, a low pressure CVD apparatus with a source gascomprising pentaethoxyltantalum (Ta(OC₂H₅)₅) gas and oxygen can be usedto form the tantalum oxide film 32A. The deposited tantalum oxide film32A can be either an amorphous or crystalline film. The thickness of thefilm 32A can be in the range of several angstroms (Å) to several hundredÅ, and should be optimized to obtain a desired capacitance.

[0039] After the film 32A is deposited, it is subjected to a densifyingtreatment by which the oxide film 32 (FIG. 6) is formed. The densifyingtreatment includes heating the semiconductor wafer to stabilize and/orcrystallize the film 32A and includes subjecting the wafer to a wetoxidation in a rapid thermal process (RTP) chamber. Performing a wetoxidation process in an RTP chamber to form the film 32 can help reducethe leakage current of the dielectric film without significantlyreducing its capacitance. In particular, the tight temperature controlprovided by the RTP process allows the wet oxidation to be performedquickly so that the oxidizing species does not diffuse significantlythrough the dielectric film and distort the capacitance.

[0040] The RTP chamber 50 described above can be used to perform the wetoxidation of the film 32A. Furthermore, the various techniques describedabove for providing steam to the RTP chamber interior with respect toformation of the gate dielectric film 12 also can be used to form thecapacitive dielectric film 32. In particular, the steam for the wetoxidation of the film 32A can be provided to the interior of the RTPchamber using a bubbled water vapor technique, a pyrogenic system, or acatalytic system. Alternatively, an in situ steam generation process canbe used. The various process parameters, such as temperature, pressure,and mixtures of gases, discussed above with respect to formation of thegate dielectric 12 can be used during wet oxidation of the film 32A aswell.

[0041] In some applications, the RTP process performed for the wetoxidation is sufficient to stabilize the gate dielectric film 12 or thefilm 32 as desired. For example, if an amorphous film 12 or 32 isdesired, the wet RTP oxidation may suffice. However, in some cases, itis desirable to subject one or both of the films 12, 32 to a heattreatment in an ambient having a stabilizing gas comprising nitrogen(N₂), oxygen (O₂ or O₃), nitrogen oxide (NO), or nitrous oxide (N₂O)just prior to or after performing the respective RTP wet oxidation (seeFIG. 8). Such a stabilizing process can be used, for example, to obtaina crystalline film. Although the stabilizing process can be performed ina separate furnace, performing the stabilizing process in the same or adifferent RTP chamber can provide tighter temperature control. The totaltime required for conditioning the dielectric film 12 (or 32) using theRTP process can be on the order of several minutes per wafer.

[0042] In some implementations, the stabilizing process can is performedwhile the temperature in the RTP chamber is brought to the temperaturefor the wet oxidation. The wet oxidation should be performed at atemperature slightly less than the temperature for the stabilizingprocess so that the properties of the film 12 (or 32) obtained duringthe stabilizing process are not adversely affected by the subsequent RTPwet oxidation. Thus, in one implementation, the dielectric film 32Ainitially is subjected to an ambient comprising N₂ at a temperaturegreater than about 750° C. The wet RTP oxidation subsequently isperformed at a temperature in the range of about 500 to 700° C. In analternative embodiment, the film 32A initially is subjected to the wetRTP oxidation at a temperature in the range of about 500 to 700° C.Subsequently, the oxidized film 32 is subjected to dry N₂ or O₂ at atemperature greater than about 700° C. As previously mentioned, the wetoxidation combined with the higher temperature stabilization can be usedto form a crystalline dielectric film.

[0043] Once the densification process for the film 32 is complete, theupper electrode 36 is formed, for example, by depositing and patterninga titanium nitride film as shown in FIG. 7.

[0044] Although the techniques have been described with respect tomemory cells such as DRAMs, the techniques also can be used with othersemiconductor devices incorporating insulating or dielectric films,particularly where the as-deposited insulating film is oxygen deficientor more leaky than desired. The foregoing techniques can be used toenhance the oxygen content of the as-deposited dielectric film withoutadversely affecting other electrical properties of the film or theinterface between the dielectric film and an underlying layer.

[0045] Other implementations are within the scope of the followingclaims.

What is claimed is:
 1. A method of fabricating a semiconductor device,the method comprising: depositing an oxygen-deficient dielectric film;and subjecting the dielectric film to a wet oxidation in a rapid thermalprocess chamber at a temperature of at least about 450° C. to increasethe oxygen content of the dielectric film.
 2. The method of claim 1wherein the wet oxidation process is performed at a temperature in arange of about 450° C. to about 750° C.
 3. The method of claim 1 whereinthe wet oxidation process is performed at a temperature in a range ofabout 750° C. to about 950° C.
 4. The method of claim 1 wherein theoxidation process is carried out for a duration in a range of about 20to about 60 seconds.
 5. The method of claim 1 wherein subjecting thedielectric film to a wet oxidation includes heating a mixture ofhydrogen and oxygen gases wherein the ratio of steam to other gases inthe chamber is in the range of about 0.1 to about 0.5.
 6. The method ofclaim 1 wherein subjecting the dielectric film to a wet oxidationincludes heating a mixture of hydrogen and oxygen gases wherein theratio of hydrogen gas to oxygen gas in the mixture is in the range ofabout 0.1 to about 0.8.
 7. The method of claim 1 wherein subjecting thedielectric film to a wet oxidation is performed for a duration such thatan oxidizing species does not diffuse significantly through thedielectric film into an underlying layer.
 8. The method of claim 1wherein depositing a dielectric film includes depositing a materialhaving a dielectric constant of at least about
 25. 9. The method ofclaim 1 further including: subjecting the dielectric film to a heattreatment in an ambient comprising a stabilizing gas selected from thegroup consisting of N₂, O₂, O₃, NO, and N₂O.
 10. The method of claim 9wherein subjecting the dielectric film to a heat treatment in an ambientcomprising a stabilizing gas is performed prior to subjecting the filmto the wet oxidation.
 11. The method of claim 9 wherein the wetoxidation is performed at a temperature less than the temperature forsubjecting the dielectric film to a heat treatment in an ambientcomprising a stabilizing gas.
 12. The method of claim 9 whereinsubjecting the dielectric film to a heat treatment in an ambientcomprising a stabilizing gas is performed in the rapid thermal processchamber.
 13. A method of fabricating a semiconductor device, the methodcomprising: depositing a dielectric film over an active region of asemiconductor substrate to form a gate of a transistor; and subjectingthe dielectric film to a wet oxidation in a rapid thermal processchamber at a temperature greater than about 450° C.
 14. The method ofclaim 13 wherein the wet oxidation is performed at a temperature in arange of about 750° C. to about 950° C.
 15. The method of claim 13wherein the oxidation process is carried out for a duration in a rangeof about 20 to about 60 seconds.
 16. The method of claim 13 whereindepositing a dielectric film includes depositing a material having adielectric constant of at least about
 25. 17. The method of claim 13wherein depositing a dielectric film includes depositing a materialselected from the group consisting of tantalum oxide and siliconnitride.
 18. A method of fabricating a semiconductor device, the methodcomprising: depositing a dielectric film over an active region of asemiconductor substrate to form a gate of a transistor; and providingsteam to a vicinity of the dielectric film while the substrate is in arapid thermal process chamber at a temperature greater than about 450°C.
 19. The method of claim 18 wherein providing steam includes heating amixture of hydrogen and oxygen gases, and wherein the ratio of steam toother gases in the chamber is in the range of about 0.1 to about 0.5.20. The method of claim 18 wherein providing steam includes heating amixture of hydrogen and oxygen gases wherein the ratio of hydrogen gasto oxygen gas in the mixture is in the range of about 0.1 to about 0.8.21. The method of claim 18 wherein the steam is provided to the rapidthermal process chamber using a bubbled water vapor system.
 22. Themethod of claim 18 wherein the steam is provided to the rapid thermalprocess chamber using a pyrogenic system.
 23. The method of claim 18wherein the steam is provided to the rapid thermal process chamber usinga catalytic system.
 24. The method of claim 18 wherein providing steamto a vicinity of the dielectric film includes generating steam in thechamber in situ.
 25. The method of claim 18 further including:subjecting the dielectric film to a heat treatment in an ambientcomprising a stabilizing gas selected from the group consisting of N₂,O₂, O₃, NO, and N₂O.
 26. A method of fabricating a capacitive elementfor a semiconductor device, the method comprising: forming a lowerelectrode of the capacitive element; depositing a dielectric film overthe lower electrode; subjecting the dielectric film to a wet oxidationin a rapid thermal process chamber at a temperature of at least about450° C.; forming an upper electrode of the capacitive element over thedielectric film.
 27. The method of claim 26 wherein the wet oxidation isperformed at a temperature in a range of about 750° C. to about 950° C.28. The method of claim 26 wherein the oxidation process is carried outfor a duration in a range of about 20 to about 60 seconds.
 29. Themethod of claim 26 wherein depositing a dielectric film includesdepositing a material having a dielectric constant of at least about 25.30. The method of claim 26 wherein depositing a dielectric film includesdepositing a material selected from the group consisting of tantalumoxide, silicon nitride, barium strontium titanate, strontium titanate,lead zirconium titanate and strontium bismuth tantalate.
 31. The methodof claim 26 further including: subjecting the dielectric film to a heattreatment in an ambient comprising a stabilizing gas selected from thegroup consisting of N₂, O₂, O₃, NO, and N₂O.
 32. The method of claim 26wherein the wet oxidation is performed for a duration such that anoxidizing species does not significantly affect capacitive properties ofthe dielectric film.
 33. A method of fabricating a capacitive elementfor a semiconductor device, the method comprising: forming a lowerelectrode of the capacitive element; depositing a dielectric film overthe lower electrode; providing steam to a vicinity of the dielectricfilm in a rapid thermal process chamber at a temperature of at leastabout 450° C.; and forming an upper electrode of the capacitive elementover the dielectric film.
 34. The method of claim 33 wherein providingsteam includes heating a mixture of hydrogen and oxygen gases andwherein the ratio of steam to other gases in the chamber is in the rangeof about 0.1 to about 0.5.
 35. The method of claim 33 wherein providingsteam includes heating a mixture of hydrogen and oxygen gases whereinthe ratio of hydrogen gas to oxygen gas in the mixture is in the rangeof about 0.1 to about 0.8.
 36. The method of claim 33 wherein the steamis provided to the rapid thermal process chamber using a bubbled watervapor system.
 37. The method of claim 33 wherein the steam is providedto the rapid thermal process chamber using a pyrogenic system.
 38. Themethod of claim 33 wherein the steam is provided to the rapid thermalprocess chamber using a catalytic system.
 39. The method of claim 33wherein providing steam to a vicinity of the dielectric film includesgenerating steam in the chamber in situ.
 40. The method of claim 33wherein providing steam to a vicinity of the dielectric film isperformed for a duration such that an oxidizing species does not diffusesignificantly through the dielectric film so as to oxidize the lowerelectrode.